kennedy



3 Sheets-Sheet 1. R. KEN N E D Y. ELECTRICAL TRANSFORMER.

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Patented Mar. 8

fiwenor: Rankin/Ken U y w (No Model.) 3 Sheets-Sheet 2.

Y R. KENNEDY.

ELECTRICAL TRANSFORMER.

No. 447,569. Patented Mar. 3,1891.

mwmw Z/m WW (No Model.)

. R. KENNEDY. ELECTRICAL TRANSFORMER.

3 Sheets-Sheet 3.

Patented Mar. 3,1891.

Inventor.

\lgme sse5= UNITED STATES PATENT -OFFICE.

RANKIN KENNEDY, OF GLASGOW, SCOTLAND, ASSIGNOR OF ONE-HALF TO ROBERT DICK, OF SAME PLACE.

ELECTRICAL TRANSFORM ER.

SPECIFICATION forming paid: of Letters Patent No. 447,569, dated March 3, 1891.

Application filed December 29, 1886. Serial No. 222,929- (No mode l.)

To all whom it may concern.-

Be it known that I, RANKIN KENNEDY, a subject of the Queen of Great Britain and Ireland, and a resident of Glasgow, county of Lanark, Scotland, have invented certain Improvements in the Transformation and Distribution of Electric Energy, of which the fol lowing is a specification.

My invention has for its object and comprises appliances for the distribution of electric energy in alternating currents from a center with safety, economy, and cheapness. The distributingwires employed for the purpose of this invention are comparatively small and light, a large amount of energy being transmitted in the form of a small current at a high pressure or electro-motive force. Thus a horse-power can be transmitted through a wire only one-tenth of an inch in diameter with a loss of only one-tenth of a horse-power per thousand yards of wire if I maintain a pressure or electro-motive force at the distant ends of one hundred and fifty volts and maintain a current of five amperes. If I multiply the pressure by ten and raise it to fifteen hundred at the distant ends and still maintain a current of five amperes, this Wire a'tenth of an inch in diameter will transmit ten horse-power with a loss of or rather at the expenditure of only one-tenth of a horsepower per one thousand yards or at a loss of only one per cent. It being thus possible to transmit electric energy at such a small loss per one thousand yards provided I employ high electro-motive force and small current it becomes of importance to apply cables or apparatus, whereby I may utilize small currents at a high pressure for electric lighting, transmission of power, and other purposes, which is what my invention is desired to accomplish. In the present state of electrical engineering small currents at high pressure cannot be conveniently applied to useful purposes generally. It is therefore necessary to transform the small currents of high pressure into the large currents of low pressure, which are demanded and required for electric lighting and other purposes.

Electric energy is equal to the current multiplied by the electro-mot-ive force or press ure, and the product divided by seven hundred and forty-six watts is equal to the horse-,

power of the energy. Thus, if I have fifteen hundred volts pressure and five amperes current the energy would be equal to (fifteen:

hundred multiplied by five equals seven thousand five hundred, divided by seven hundred and forty-six, equals) about ten horse-power. Now,if this were transformed into a safe and usual pressuresay one hundred volts and a current of seventy-five ampres-I would still have the same amount of energy in a useful and applicable form, or (one hundred multiplied by seventy-five equals seven thousand five hundred, divided by seven hundred and forty-six, equals) about ten horse-power, as before, and the said current at this pressure could be utilized to light up and maintain one hundred sixteen-candle incandescent lamps,

and all transmitted through a wire one-tenth of an inch thick one thousand yards long, and

at aloss in the wire of only one-tenth of a horse-power.

I have found as general laws governing the distribution of electric energy, first, where the consumption-circuits require constant electromotive force the transformers should be connected in parallel or multiple arc order and supplied from main conductors at constant electro-motive force; second, when the consumption-circuit requires a constant current I have found that the transformers should be connected in series order to the mains and a constant current maintained in these mains; third, it is necessary for the purposes of economy and the supply of constant electromotive force to the consumption-circuits that the transforming device, whether in the form of a machine, cable, or induction-coil, should, when the secondary or consumption-circuit is open, or, in other words, when no consump tion is going on, generate a counter electromotive force nearly equal and opposite to the working electro-motive force in the main conductors, and also that th-'"-3 enter r opposin g electro-motive force should decrease regularly and steadily as the consumption increases; fourth, where a constant current is to be maintained in the mains and a constant current supplied to the consumption-circuit According to my present improvements for" connection in parallel order with the mains and constant potential supply, my alternating-current transformer consists of a cable or rope of insulated copper wires or strips of copper sheathed with soft iron. There may be any number of wires or strips in the cable and some may be insulated from the others, while others may be uninsulated in cases where they have to be joined parallel. Good results are obtained where only seven wires are used, a central insulated wire forming a secondary circuit and surrounded by six bare wires forming a primary circuit, the whole constituting a cable, which is then insulated bya layer of cotton, silk, or jute tape covering all over. Over this is then wound a sheathing of soft iron, either of coiled wire, plates, or ring disks, preferably to a depth of from an eighth to a fourth of the diameter of the seven-wire cable. The cable when used as a transformer may be coiled or put up into any shape or form most convenient for its being packed away.

In the accompanying drawings, Figures 1 and 2 are transverse and longitudinal vertical sections, respectively, of a cylindrical form of alternating-current cable or transformer constructed in accordance with my said improvements, in which one large insulated copper round wire a. is used as the secondary-circuit conductor and six smaller insulated wires a, connected up in series order, are used as the primary-circuit conductor, both conductors constituting a cable or transformer which is covered over with a layer of cotton, silk, jute tape, or other insulating material c, and having an insulating material between the wires, (indicated at c,) and over the whole is then applied a sheathing of coiled soft-iron insulated wire 1) outside, as shown at one end of Fig. 2; or it might be annular thin disks of soft sheet-iron, as shown at b b in Fig. 2 and in end view in Fig. 3, these rings or plates being also insulated from each other by :1 c a ii .Jf varnish or by thin strips of paper and made to inclose the whole cable or coil from end to end. Instead of using round iron wire for the primary and secondary circuit conducting-wires, flat or polygonal wires may be used.

Fig. 4e is a transverse section, and Figs. 5

and 6 are longitudinal sections at right angles to each other, respectively, of amodified construction of alternating-current cable or transformer from the cylindrical form shown in Figs. 1, 2, and 3, and which is rectangular in transverse section, as shown in Fig. 4, constructed in accordance with the improvements of my invention. In this construction the primary-circuit conductors a and the secondary-circuit conductors a consist of six narrow and four broad strips or bands, respectively, of copper insulated from each other by a layer of cotton or other insulating material c, which may either be wound round the bands or compressed between them and 'a'll inclosed within an insulating-covering 0, (indicated in-gray and black lines, respectively,) while the bands of copper are shown in section in Fig. 4. In this arrangement the primary-circuit conductors a are connected up in series order and the secondarycircuit conductors a in parallel order. This cable or cable-transformer is inclosed within a magnetic sheathing, casing, or shell of coiled wire or narrow bands b or ring-plates I), re spectively, as described in reference to Figs. 1 to 3, an end view of one of these metallic ring-plates being shown in Fi 7. These ringplates 12' (shown in Figs. 3 and 7) might be punched out of soft sheet-iron as washers are usually punched.

Fig. 8, Sheet 2, illustrates a perspective view showing how my new or improved cable-transformer can be used in a system of distribution of electric energy for supplying any desired electro-motive force up to the maximum to the electric lamps or other translating devices placed in the consumption-circuit. In this arrangement the secondary wire in the transformer is connected at A to the main conducting-wire A, which is connected to the translating devices g at G, and at the different points B C D E connection is made by the IIO wires II between the secondary wire of the transformer and a switch-board F, having separate studs numbered 1 2 3 4. for each of these respective wires or contacts.

The main conducting-wire B is connected to the movable switch or contact-maker F, so that any desired electro-motive force is conveyed to the lamps or other translating devices g, placed at G, according to the stud with which the movable switch is placed in contact.

In the diagram, Fig. 9, I have illustrated how the cable in practice is made up into a coil and how the primary and secondary wires are connected in series. In this figure the primary wires (indicated by thin lines) are distinguished by numerical figures 1 to 6 and the connections by light dotted lines. The first wire 1, which forms the one terminal end at m for current connection, has its other end 1' connected to the next wire 2, and the wire 2 has its other end 2' connected to the next wire 3, and the wire 3 has its other end 3 connected to the next wire 4-, and the Wire 4.

has its other end 4 connected to the next wire 5, and the wire 5 has its other end 5 connectedto the next Wire 6, and so on, if there are more primary wires in the cable. In this case the other end 6 of the wire 6 forms the other terminal end no of the primary wires thus joined in series for current connection, the ends a: and x of the wires 1 and (3 being connected to the conductors leading from the alternating-current generator. The secondary wires a b c, which are indicated by thick lines and the connections by thick dotted lines, are also in this case connected in series. The first wire a is connected at the end a to the next wire I), and the wire Z) has its other end I) connected to the next wire 0, and so on, if there are more secondary wires. In this case the free ends y and of the wires a and c are connected to the main conductorsof the consumption-circuit, as A and B in Fig. 8, through which currents would be transmitted when currents pass through the primary wires. The primary and secondary wires would be covered and embedded in insulating material, such as gutta-percha, and have a magnetic-iron outside sheathing of a few layers of coiled wire b and, as indicated by b in Figs. 1 to- 6, over the whole length, so as to form an iron-sheathed cable-transformer.

The novel feature in these improvements is the application of an iron-sheathed cable of insulated conducting-wires, wherein one or more wires are used as a primary and one or more as a secondary circuit for the transformation of electric energy of alternating currents.

Iron sheathing has heretofore been applied to coils of wire for the same purpose; but in that case, the coils of wire being of many turns, some of them are unavoidably far from the iron sheathing, and thus its effects are not uniform throughout the length of wire forming the coils.

By my improvements I inclose the wires themselves from end to end in an iron sheathing, and this insures uniformity, besides great intensity of action, from end to end, and I do not require to wind this cable into any particular coil or form whatever. This improved cable is also conveniently made in long lengths of any suitable crosssection sufficient to carry the strength of current. For instance, if I have a current of six amperes in the pri mary-circuit wire a, that would in practice require to have a sectional area of at least two square millimeters. In the secondary circuit, where the large currents circulate, the combined area of the wires a forming this circuit would be equal to one square millimeter for every three amperes of current.

In my improved cable the electro-motive force is directly proportional to its lengththat is to say, the force increases from zero at one end to a maximum at the other-so that any desired electro-motive force less than this maximum may be obtained by making a connection at proportionally lesser lengths of the cable, as shown in Fig.8, Sheet 2. Thus with a cable of a length giving a hundred volts pressure an electro-motive force of fifty volts could be obtained by makin g a connection at half-length and still maintain the continuity of the cable and the maximum pressure of the whole length; or the cables may be made in coils of suitable lengths as transformers for any desired electro-motive force to be transmitted through them.

It is to be understood that this cable or cable-coil transformer, although described as a secondary generator, may also be used as a main transformer of alternating currents of electric energy when placed between the dynamo-electric machines and the main conductors for transforming currents of low potential into currents of high potential in the main lines by having the primary conductor as a short wire and the secondary conductor as a long wire.

\Vhat I claim is- 1. A cable for transformers of electric en ergy having insulated copper conductors forthe primary and secondary circuits inclosed throughout their length within an outer sheathing of iron wires or plates, substantially as and for the purpose set forth.

2. A transformer of electric energy in the form of a cable and comprising the combination of an outer sheathing of iron wires or plates with inner primary and secondary wires having connections made at any numher of points along the length of thebable for the purpose of obtaining any desired electro-motive force less than the maximum,'substantially as herein set forth.

In testimony whereof -I have signed my name to this specification in the presence of two subscribing witnesses.

RANKIN KENNEDY. Witnesses:

W. R. M. THOMSON, JOHN SIME, Both of 96 Buchanan St, "at, Glasgow. 

